The subject invention relates generally to the field of bulk material pipe systems adapted to convey highly abrasive materials from one location to another by liquid, pneumatic and vacuum movement and, more particularly, to pipes for such systems having highly wear resistant inner linings.
In many types of industrial and commercial operations, highly abrasive materials such as coal, coke, ore, ash, sand and grain are transported in bulk from one location to another through pipeline systems by fluid movement of the material. Depending upon the precise application, the material may be transported pneumatically or in a slurry through the pipeline system. Because materials such as those listed above are highly abrasive, the pipe sections through which the materials are transported are subject to a high degree of wear. In fact, one of the present major causes of breakdowns in such piping systems is due to wearing away of a portion of the pipe from such abrasive contact. Even hardened or stainless steel pipe casings can be abraded away in a matter of a few months when subjected to the sliding contact of abrasive materials conveyed therethrough.
Since bulk material handling systems of the type described above are a vital link in the operation of many heavy industrial plants, power generating companies, etc., it is of great importance to keep such systems operable for a maximum portion of time. In the past, this has been accomplished by using pipe sections having highly wear resistant inner linings, such as ceramic, at least along those sections of the pipe system for which high wear is reasonably anticipated. Depending upon the material construction for the inner lining, pipe sections having wear resistant inner linings can last several and even many times longer than pipe sections having standard steel or even hardened or stainless steel casings.
While pipe sections of the type just described have a much longer life than previous pipe sections formed of hardened or stainless steel, they will still eventually wear away in the same manner as other pipe sections, causing an unscheduled breakdown of the system. Presently, there are two basic ways to determine when a pipe section is about to wear through. The first way is by a visual inspection which necessitates a production shutdown and dismantling of the piping system for inspection purposes. Such scheduled inspections, in theory, provide a benefit in that the plant operators can plan ahead for a plant shutdown. Further, as long as a pipe section is only partially worn through, the pipe section can be rotated on its center axis to move the highly worn area of the pipe away from the area which is subject to increased wear. This practice saves the pipe section from having to be discarded long before the remainder of the pipe has lost its usefulness.
Unfortunately, it is very difficult, if not impossible, to predict where, along the length of a pipe system, abrasive contact wil be most highly concentrated and how quickly a wear through condition will occur. Thus, scheduled inspections are very costly and time consuming, especially in remote or difficult to reach areas. Further, unscheduled breakdowns can occur even when a piping system is periodically inspected. Because of these factors, performing visual inspections at periodic times is only marginally effective, and for this reason not often performed. The second and most common practice is to simply allow the various sections of the pipe system to gradually wear through and then replace such sections accordingly. This results in an unscheduled breakdown of the bulk material handling system, not to mention a substantial spillage of material. Depending upon the production schedule of the plant, either a plant shutdown is effected or other temporary remedial action is taken until such time as the worn section can be more conveniently scheduled for replacement.